Re: TTML2 comments on roll-up and paint-on captions

At present, one might say that TTML always operates in paint on mode, in
the sense that if some content is active at a given time it is painted on
at that time.

As for rollup mode, how would you control the timing of when content is
added to a region? Current 608/708 content is implicitly timed by its
binding to video content, but how would this occur if spans were not timed
so as to cause them to become active in a region at a given time?

On Wed, Jul 12, 2017 at 4:17 PM, Goldstein, Glenn <
glenn.goldstein@viacom.com> wrote:

> In my opinion, the approach taken for supporting roll-up and paint-on
> modes (2 important caption styles in the US) could be simplified by having
> explicit regions attributes, as in tts:paintmode=”rollup” or
> tts:paintmode=”painton”. For rollups, the scrolling style could also be
> designated as “smooth” or “discrete”.
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> This approach would simplify the conversion of 608/708 captions to TTML,
> and eliminate the complexity and clutter of overlapping cues and timed
> <span> tags.
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> Glenn Goldstein
>
> SVP, Chief Technology Convergence Officer
>
> Viacom MTS
>
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>